In an elevator, generally, an elevator car suspended by a rope moves up and down along a pair of guide rails laid in an elevator shaft vertically. Although the elevator car swings due to disequilibrium of loads or movements of passengers, these swing movements are suppressed since the elevator's traveling is guided by the guide rails.
As for guiding units for an elevator car, either roller guides having wheels rolling on the guide rail and suspensions or guide shoes sliding on the guide rail have been adopted in the past. In a contact-type guide like this, however, there is a case that the amenity of an elevator is damaged since vibration and noise originating in a distortion of the guide and its joints are transmitted to the interior of the elevator car through the guiding units, or due to rolling noise originating in the roller guide in rotation sound.
In order to solve such a problem, there is proposed a method of guiding the elevator car in non-contact with the guide rails, as shown in the following Patent Document No. 1. Here, guiding units having electromagnets are mounted on the elevator car to apply magnetic force on the guide rails made of iron.
In this method, each magnetic force between the guide rail and the guiding unit is controlled by exciting the electromagnets arranged on four corners of the elevator car and each surrounding the guide rail in three directions, allowing the guide rail to guide the elevator car in non-contact manner.
In the following Patent Document No. 2, there is further proposed a structure where the guiding unit is provided with a permanent magnet as means for solving both reduction in controllability and increase in electric power consumption, both of which are present problems for the guiding unit for an elevator in accordance with the above-mentioned method.
Thus, with use of the permanent magnets in combination with the electromagnet, it is possible to offer an elevator capable of guiding an elevator car with soft-suspention and long stroke while consuming lower amounts of power.
Patent Document No. 1: Japanese Patent Application Laid-open (Heisei) No. 5-178563
Patent Document No. 2: Japanese Patent Application Laid-open No. 2001-19286